[libvirt] what determines the type of virtual NIC in libvirt (veth or tap)?

Hi All, I'd like to know what determines the type of virtual NIC in libvirt ? There was a problem I encountered, the vm can't get the mirror traffic while the virtual port in openvswitch is veth, If the virtual port is tun, the everything is fine. [root@allinone-247 ~]# ethtool -i vn62f717800 driver: veth version: 1.0 firmware-version: expansion-rom-version: bus-info: supports-statistics: yes supports-test: no supports-eeprom-access: no supports-register-dump: no supports-priv-flags: no I uninstall the veth kernel module, then restart vm, then the vm can receive the mirror traffic [root@allinone-247 ~]# ethtool -i vn62f717800 driver: tun version: 1.6 firmware-version: expansion-rom-version: bus-info: tap supports-statistics: no supports-test: no supports-eeprom-access: no supports-register-dump: no supports-priv-flags: no so, I'm wondering if there are configuration options which can be configured to use which type of virtual NIC(tap or veth). Any comments would be appreciate.